As polymer materials, asphalt has a certain self-healing or self-rehabilitation capacity and thus is widely applied to roads. In the long-term service process, asphalt components may be changed under the effects of external environmental factors such as sunlight irradiation and rain washing as well as certain internal chemical reactions, inevitably resulting in some tiny cracks and local damage. Without timely control over such micro-damage, these tiny cracks will further expand under the effect of external loads, which will in turn affect the service life of roads. Although asphalt regenerants may be used for compensating asphaltene micromolecules, the direct penetration depth of the asphalt regenerants is not over 2 cm.
Studies have shown that the restoration capacity of asphalt can be improved by wrapping asphalt restoration agents through the microencapsulation technology that enables the restoration agents to be dispersed in the asphalt in the droplet form. Microencapsulation technology is a self-restoration method based on substance supplementation. By wrapping capsule cores with capsule walls, microcapsules will be stimulated when materials are cracked, then the capsule walls break to release the capsule cores to compensate for components of the asphalt that are lost due to aging, and thus the restoration effect is achieved.
CN106732222A discloses an asphalt crack self-restoration microcapsule and a preparation method thereof. The asphalt crack self-restoration microcapsule includes, by mass, 30-50 parts of methylated melamine-formaldehyde resin prepolymer, 20-50 parts of asphalt regenerant, 2-5 parts of styrene-maleic anhydride copolymer, 0.5-2 parts of graphene and 80-120 parts of distilled water. The preparation method of the asphalt crack self-restoration microcapsule includes the following steps. 1) Styrene-maleic anhydride of the constituent quantity is added to distilled water to be swelled for 2-3 hours, an alkaline PH regulator is dropwise added to an obtained solution regulate the PH of the solution to 10-11 until the PH of the solution is stable, and then the solution is stirred for 2-3 hours; 2) graphene of the constituent quantity is added to the solution obtained in step 1) and then ultrasonically oscillated to be evenly mixed, and afterwards, an asphalt regenerant of the constituent quantity is added to the solution and mechanically stirred and emulsified for 10 min-30 min in a high-speed dispersion machine at a preset stirring speed of 700-1200 rpm to obtain an oil-in-water emulsion attached with graphene; and 3) the stirring speed is regulated to 300-400 rpm, then methylated melamine-formaldehyde resin of the constituent quantity is dropwise added to the oil-in-water emulsion at a dropping speed of 0.5-5 ml/min, afterwards, the oil-in-water emulsion is heated to 40-50° C. and then slowly heated to 70-90° C. at a speed of 2° C./min, the temperature is maintained for 10 min every time increased by 5° C., after the oil-in-water emulsion is heated to 70-90° C., an acid pH regulator aqueous solution of the constituent quantity is dropwise added to the oil-in-water emulsion to regulate the pH to 10, the oil-in-water emulsion continues to be solidified for 1-2 h, and finally is slowly cooled to the room temperature at a cooling speed of 2° C./min, centrifuged to separate out a product and diluted with water for centrifugal separation again, and the asphalt crack self-restoration microcapsule is obtained after vacuum drying. In this method, due to the fact that no chemical bond is formed between wall resin and graphene, the graphene fails to firmly adhere to the wall surface, resulting in a negative influence on electrical conductivity.
Moreover, ice-snow covered pavements are always a hot topic in road engineering studies as snow and ice accumulated on roads severely affect the transportation condition, particularly in alpine regions. Nowadays, asphalt pavements are typically passively maintained and protected against freezing; however, all these methods have the requirement for applying external forces to the pavements, resulting in a high cost, a poor effect and negative influences on the ambient environment in the construction process.
In light of this, it is extremely urgent to realize good aging resistance and ice and snow resistance of asphalt pavements for the current high-traffic, high-load transportation environment.